1. From the Departments of Radiology (C.H.O.K., T.J.D., C.W.A.P., R.S.) and Orthopedic Surgery (P.O.Z., C.D.), Orthopedic University Hospital Balgrist, Forchstrasse 340, 8008 Zurich, Switzerland; and Faculty of Medicine, University of Zurich, Zurich, Switzerland (C.H.O.K., T.J.D., P.O.Z., C.D., C.W.A.P., R.S.).